Which Countries Have the Strongest Submarine Fleets?

TL;DR

Submarine strength depends on stealth, endurance, weapons, and operational readiness, not fleet size alone. Nuclear-powered boats can patrol quietly over long distances, while most diesel submarines must surface periodically to recharge; smaller fleets mainly defend nearby waters, whereas China, Russia, and other major powers use submarines to project power and support nuclear deterrence.

Transcript

• This is every military submarine on earth, at least the ones we know about. I've separated them out by each country. "Whoever rules the waves rules the world," is a saying that rings especially true in recent years as global power dynamics are shifting before our eyes. Submarines represent ocean power. So today, let's look at the 471 known milita... Read More

Key Insights

• At least 471 known military submarines are divided among 43 countries, though experts disagree about exact totals. Most submarine-operating countries maintain fleets of fewer than a dozen vessels, reflecting the high strategic value that even one difficult-to-locate submarine can provide.
• A submarine's central advantage is uncertainty about its location. Because an opponent cannot easily know where a hidden boat is patrolling, it must consider that surveillance or an attack could come from many places, giving even small fleets significant defensive value.
• Most smaller submarine fleets use diesel engines that require oxygen and must periodically recharge onboard batteries near the surface. Running those engines creates noise and exposure, making these boats less persistent and potentially easier to detect than nuclear-powered submarines.
• Nuclear-powered submarines can remain underwater without surfacing for air because their reactors provide sustained energy. The onboard process also produces oxygen and drinkable water, so food and other supplies for the crew become the practical constraints on exceptionally long submerged patrols.
• Israel's five modern submarines serve as a regional deterrent, and two can remain underwater for up to a week without taking in oxygen. The transcript says the US government believes Israeli submarines can carry nuclear-warhead missiles, although Israel denies that capability.
• Australia's planned nuclear-powered submarines are part of a historic arrangement with the United States and United Kingdom. The plan illustrates how the United States is strengthening alliances near China and how nuclear propulsion can shift a navy from coastal defense toward longer-range power projection.
• North Korea's fleet demonstrates why quantity alone can mislead. Experts estimate that it could have as many as 85 submarines, while the presentation uses a conservative figure of 36, but some boats are at least 50 years old and their operational condition is disputed.
• China's 58-submarine fleet includes six nuclear-missile boats and six nuclear-powered attack submarines, but most of its vessels are older diesel designs. Russia operates 62 submarines, half are nuclear-powered, and 12 can launch nuclear weapons, giving its fleet capabilities beyond raw numerical size.

Questions & Answers

Q: How many military submarines are known to exist worldwide?

At least 471 known military submarines are distributed across 43 countries, according to the figures presented. The totals remain uncertain because experts disagree about individual national inventories and some military information is secret. Most countries with submarines operate fewer than a dozen, while a small group of major powers controls much larger and more capable fleets.

Q: Why can even one submarine strengthen a small navy?

Even one submarine can strengthen a small navy because its location is difficult for an opponent to determine. That uncertainty forces potential attackers to assume the vessel could be spying, patrolling, or preparing to strike from several possible locations. Smaller navies therefore use submarines primarily to protect coastal waters and make hostile action appear more dangerous and costly.

Q: What limits a diesel-powered military submarine?

A diesel-powered submarine needs oxygen to run its engines. It must periodically move toward the surface and operate those engines to recharge its batteries before diving again. This creates a major limitation because the engines are loud and the surfacing cycle increases exposure. Diesel boats consequently have less underwater endurance than submarines powered by nuclear reactors.

Q: How does nuclear propulsion improve submarine capability?

Nuclear propulsion uses an onboard reactor that breaks apart atoms, produces immense energy, heats water, and powers the submarine. It does not require the vessel to surface for atmospheric oxygen, allowing quiet, long-distance patrols. The process also produces oxygen and drinkable water for sailors, leaving food and other human supplies as the main practical limits on endurance.

Q: Why does Israel maintain modern submarines?

Israel uses its five modern submarines to deter regional enemies, including Iran. Two of the boats can remain underwater for up to a week without taking in oxygen and can travel up to 4,500 kilometers. The transcript reports that the US government believes Israeli submarines can launch nuclear-warhead missiles, although Israel denies possessing that submarine capability.

Q: How is Australia planning to modernize its submarine fleet?

Australia currently has a relatively small fleet of diesel-powered submarines, but it plans to obtain advanced nuclear-powered boats through a historic arrangement with the United States and United Kingdom. The submarines are being purchased from the United States. The initiative forms part of a broader US effort to strengthen alliances in China's neighborhood and expand allied maritime capabilities.

Q: Why is North Korea's submarine count an incomplete measure of strength?

North Korea may have as many as 85 submarines, although the presentation uses a conservative estimate of 36 because reliable information is scarce. A large inventory does not guarantee high capability: some boats are at least 50 years old, and experts dispute how many remain functional. Only around eight diesel submarines are described as capable of long-range patrols.

Q: How do the submarine fleets of China and Russia compare?

China has 58 submarines, including six capable of firing nuclear weapons and six nuclear-powered attack submarines, but most of its fleet still consists of older diesel-powered boats. Russia has 62 submarines, half powered by nuclear energy, and 12 can launch nuclear weapons. The comparison shows that propulsion and weapon capability matter alongside total fleet size.

Summary & Key Takeaways

• The world has at least 471 known military submarines distributed among 43 countries, although experts dispute the precise figures. Most countries operate fewer than a dozen boats. Even a small fleet can strengthen coastal defense because hidden submarines force opponents to consider possible surveillance or attack across a wide area.

• Most smaller navies rely on diesel-powered submarines that must periodically approach the surface and run loud engines to recharge their batteries. Nuclear reactors remove this oxygen requirement, provide immense energy, and help produce oxygen and drinking water. Nuclear-powered boats can therefore patrol quietly across greater distances, limited mainly by human supplies.

• Fleet size does not directly measure capability. North Korea may possess numerous submarines, but some are at least 50 years old and experts question their functionality. China is expanding and modernizing a largely diesel fleet, while half of Russia's 62 submarines are nuclear-powered and 12 can launch nuclear weapons.